I am curious as to how the connection of climate change and cars, relating to roads, highways, and interstates, being what the national park system has been built on as the main way of access to parks, has been discussed?

I too am interested to see if anyone has quantitatively studied the CO2 contribution of national park visitors.  The way we have always visited national parks is tied into the Eisenhower highway system and our reliance on the family automobile.  I recall Edward Abbey proposing banning personal vehicles in parks while preserving access in Desert Solitaire.  That might not be politically feasible, but surely public transportation should have a greater role in national parks to reduce air pollution as well as ghg emissions.

Also I wonder if the NPCA or anyone else has issued a study looking at the parks' management of ecosystems in addition to funding for that management.  I know that in the past the NPS has really screwed up ecosystems in a lot of ways.

....then there would be no direct impact on the parks. But that would be rediculous.

Fundamentally, the technology under the hood must change to zero emissions if one wants to control CO2.

Even the beloved hybrids burn gasoline above 28 MPH. They may burn a bit less, but that's not the answer.

Can't go back to horses. They spew methane, (one of the top 8 greenhouse gases).

Other than staying home, hydrogen, electric or other zero emissions TBD are the only way to eliminate CO2 emissions from our modes of transport.

Whether C02 emissions occur inside the boundaries of the parks or not, its a bit like peeing in the pool.  Either next to you or on the other side, the damage is done....

Does anyone have any hard data on how horses compare to cars, pollution-wise?  I can't believe that there isn't a big difference, even if horses do emit some methane, (and what mammal doesn't?)

The average visitor is driving a SUV and is visiting a dozen national parks in the next two weeks.  I counted maybe two working-class hispanic families driving old beaters (that got probably 30+ mpg compared to the Escalades) in an entire season of working the South Rim of Grand Canyon.  Invite 5 million visitors a year and most of them drive their SUVs.  Nobody wants to talk about the huge glaring contradiction though.